This invention relates to a closure head for securing a sealing cap of the kind having a top surface, a skirt, and tear tab to a bottle opening. More particularly, this invention relates to a closure head of this general character which is capable of securing a sealing cap to a bottle opening effectively without the formation of wrinkles in the cap skirt portion.
There has previously been known a closure head for a cap which comprises a vertically slidable support sleeve arranged in a casing, a vertically movable counter-pressure plunger secured to said support sleeve, and a closure sleeve, said counter-pressure plunger being provided therethrough with a central plunger, said closure sleeve being surrounded by a pressure plunger, the upper portion of which is connected to a support ring secured to the casing and portion holds a wear ring, said closure sleeve at its lower end forming an inclined face at its outer periphery while forming at its inner periphery a fastening shoe provided with a fastening projection, said inclined face being contacted with said wear ring for sliding the latter, thereby allowing the fastening projection of the shoe to urge the skirt portion of the cap against the bottle neck to effect closure of the bottle.
In closure heads of this type, several of the closure components are rigidly connected to each other so that fine adjustment of the closure head relative to the bottle opening is difficult and damage to the bottle may occur during the closure operation. Such damage may be due to improper size or location of the bottle during the closure operation. Various adjusting mechanisms have been developed and proposed in an effort to overcome such difficulties. Especially, the applicant has developed a novel mechanism for automatically matching the sliding movement between the inclined face and the wear ring with variation of the closure operation, as disclosed in Japanese Patent Application No. 117770/82, laid-open No. 15089/84.
The closure head according to the above patent application, in which freedom of engagement between the fastening shoe of the closure sleeve and the bottle neck is large enough to solve the problems of bottle damage and poor closure of the cap during the operation, is found to be excellent. However, a common problem with such closure heads is that they tend to generate irregular wrinkles at the lower edge of the skirt, thereby forming a gap due to pressure of the fastening shoe in urging the skirt against the bottle neck, which gap may result in a poor closure and poor protection from dust entering the bottle through the gap.
An object of the invention, therefore, is to provide a new and improved closure head of the above character in which the freedom of engagement between the closure head and the bottle neck is increased so that bottle damage and poor closure are avoided, and irregular wrinkle formation in the cap skirt is prevented.